Obesity remains a serious health problem and it is no secret that many people want to lose weight. Behavioral economists typically argue that “nudges” help individuals with various decisionmaking flaws to live longer, healthier, and better lives. In an article in the new issue of Regulation, Michael L. Marlow discusses how nudging by government differs from nudging by markets, and explains why market nudging is the more promising avenue for helping citizens to lose weight.

Armed with a computer model in 1935, one could probably have written the exact same story on California drought as appears today in the Washington Post some 80 years ago, prompted by the very similar outlier temperatures of 1934 and 2014.

Two long wars, chronic deficits, the financial crisis, the costly drug war, the growth of executive power under Presidents Bush and Obama, and the revelations about NSA abuses, have given rise to a growing libertarian movement in our country – with a greater focus on individual liberty and less government power. David Boaz’s newly released The Libertarian Mind is a comprehensive guide to the history, philosophy, and growth of the libertarian movement, with incisive analyses of today’s most pressing issues and policies.

The United States was formed after a Revolutionary War against Britain so that we could live under a government more protective of liberty. The Fourth Amendment’s requirement of particularity with respect to warrants prevents our government from issuing blanket requirements that information about all of our communications be retained in case it’s needed for law enforcement.

It takes a lot of gall to put the moniker “Privacy Bill of Rights” on legislation that reduces liberty in the information economy while the Fourth Amendment remains tattered and threadbare. Nevermind “reasonable expectations”: the people’s right to be secure against unreasonable searches and seizures is worn down to the nub.

Senators Kerry and McCain [and now the White House] should look into the privacy consequences of the Internal Revenue Code. How is privacy going to fare under Obamacare? How is the Department of Homeland Security doing with its privacy efforts? What is an “administrative search”?

Does a more careful reading of the Supreme Court’s decision in U.S. v. Jones turn up a lurking victory for the government?

Modern media moves so fast that the second-day story happens in the afternoon of the first. The Supreme Court ruled unanimously Monday morning that government agents conduct a Fourth Amendment search when they place a GPS device on a private vehicle and use it to monitor a suspect’s whereabouts for weeks at a time. Monday afternoon, a couple of commentators suggested that the case is less a win than many thought because it didn’t explicitly rule that a warrant is required to attach a GPS device to a vehicle.

Writing on the Volokh Conspiracy blog, George Washington University law professor Orin Kerr noted “What Jones Does Not Hold.”

The Court declined to reach when the installation of the device is reasonable or unreasonable. … So we actually don’t yet know if a warrant is required to install a GPS device; we just know that the installation of the device is a Fourth Amendment “search.”

[D]oes the “search” caused by installing a GPS device require a warrant? The answer may be no, given that no member of the Court squarely concludes it does and four members of the Court (those who join the Alito concurrence) do not believe it constitutes a search at all.

So there is a constitutional search when the government attaches a GPS device to a vehicle, but the Court conspicuously declined to say that such a search requires a warrant. Do we have an “a-ha” moment?

When the Supreme Court granted certiorari in the case, it took the unusual step of adding to the questions it wanted addressed. In addition to “[w]hether the warrantless use of a tracking device on respondent’s vehicle to monitor its movements on public streets violated the Fourth Amendment,” the Court wanted to know “whether the government violated respondent’s Fourth Amendment rights by installing the GPS tracking device on his vehicle without a valid warrant and without his consent.” These are both compound questions, but the dimension added by the second is the Fourth Amendment meaning of attaching a device to a vehicle. The case was about attaching a device to a vehicle, and if the Court didn’t walk through every clause in each of the questions presented, that’s why.

On that central question in the case, the government argued the following: “Attaching the GPS tracking device to respondent’s vehicle was not a search or seizure under the Fourth Amendment.” The government lost, full stop.

Now, it’s true that the Court’s majority opinion didn’t explictly find that the “search” that occurs when attaching and using a GPS device requires a warrant, but look at its characterization of the opinion it affirmed: “The United States Court of Appeals for the District of Columbia Circuit reversed [Jones’s] conviction because of admission of the evidence obtained by warrantless use of the GPS device which, it said, violated the Fourth Amendment.”

The Court did decline to consider the argument that the government might be able to attach a device based on reasonable suspicion or probable cause—that argument was “forfeited” by the government’s failure to raise it in the lower courts—but if the Supreme Court were limiting its holding to the attachment-as-search issue, it would have remanded the case back to the lower courts for further proceedings consistent with the opinion. It did not, and the sensible inference to draw from that is that the general rule applies: a warrant is required in the absence of one of the customary exceptions. Failing to make that explicit was not “opening a door” to a latent government victory. U.S. v. Jones was a unanimous decision rejecting the government’s warrantless use of outré technology to defeat the natural privacy protections provided by law and physics.

At least one serious lawyer I know has raised the point that I address here, and it is a real one, but some in the commentariat are a little too showy with their analysis and far too willing to go looking for a government victory in what is nothing other than a government defeat.

The Supreme Court has delivered a big win for privacy in U.S. v. Jones. That’s the case in which government agents placed a GPS device on a car and used it to track a person round-the-clock for four weeks. The question before the Court was whether the government may do this in the absence of a valid warrant. All nine justices say No.

That’s big, important news. The Supreme Court will not allow developments in technology to outstrip constitutional protections the way it did in Olmstead.

Olmstead v. United States was a 1928 decision in which the Court held that there was no Fourth Amendment search or seizure involved in wiretapping because law enforcement made “no entry of the houses or offices of the defendants.” It took 39 years for the Court to revisit that restrictive, property-based ruling and find that Fourth Amendment interests exist outside of buildings. “[T]he Fourth Amendment protects people, not places” went the famous line from Katz v. United States (1967), which has been the lodestar ever since.

For its good outcome, though, Katz has not served the Fourth Amendment and privacy very well. The Cato Institute’s brief argued to the Court that the doctrine arising from Katz “is weak as a rule for deciding cases.” As developed since 1967, “the ‘reasonable expectation of privacy’ test reverses the inquiry required by the Fourth Amendment and biases Fourth Amendment doctrine against privacy.”

Without rejecting Katz and reasonable expectations, the Jones majority returned to property rights as a basis for Fourth Amendment protection. “The Government physically occupied private property for the purpose of obtaining information” when it attached a GPS device to a private vehicle and used it to gather information. This was a search that the government could not conduct without a valid warrant.

The property rationale for deciding the case had the support of five justices, led by Justice Scalia. The other four justices would have used “reasonable expectations” to decide the same way, so they concurred in the judgement but not the decision. They found many flaws in the use of property and “18th-century tort law” to decide the case.

Justice Sotomayor was explicit in supporting both rationales for protecting privacy. With Justice Scalia, she argued, “When the Government physically invades personal property to gather information, a search occurs.” This language—more clear, and using the legal term of art “personal property,” which Justica Scalia did not—would seem to encompass objects like cell phones, the crucial tool we use today to collect, maintain, and transport our digital effects. Justice Sotomayor emphasized in her separate concurrence that the majority did not reject Katz and “reasonable expectations” in using property as the grounds for this decision.

Justice Sotomayor also deserves special notice for mentioning the pernicious third-party doctrine. “[I]t may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties.” The third-party doctrine cuts against our Fourth Amendment interests in information we share with ISPs, email service providers, financial services providers, and so on. Reconsidering it is very necessary.

Justice Alito’s concurrence is no ringing endorsement of the “reasonable expectation of privacy” test. But he and the justices joining him see many problems with applying Justice Scalia’s property rationale as they interpreted it.

Along with the Scalia-authored Kyllo decision of 2001, Jones is a break from precedent. It may seem like a return to the past, but it is also a return to a foundation on which privacy can be more secure.

More commentary here in the coming days and weeks will explore the case’s meaning more fully. Hopefully, more Supreme Court cases in coming years and decades will clarify and improve Fourth Amendment doctrine.

That’s NYPD Commissioner Ray Kelly touting a new technology called “terahertz imaging detection” to a local news outlet.

Terahertz radiation is electromagnetic waves at the high end of the infrared band, just below the microwave band. The waves can penetrate a wide variety of non-conducting materials, such as clothing, paper, cardboard, wood, masonry, plastic, and ceramics, but they can’t penetrate metal or water. Thus, directing terahertz radiation at a person and capturing the waves that bounce off them can reveal what is under their clothes without the discomfort and danger of going “hands-on” in a search for weapons. Many materials have unique spectral “fingerprints” in the terahertz range, so terahertz imaging can be tuned to reveal only certain materials. (In case you’re wondering, I got this information off the top of my head…)

Will the machines be tuned to display only particular materials? Or will they display images of breasts, buttocks, and crotches? The TSA’s “strip-search machines” got the moniker they have because they did the latter—until the agency tardily re-configured them.

Then there’s the flip-side of not going “hands-on.” Terahertz imaging detection doesn’t natively reveal to the person being searched that law enforcement has picked him or her out for scrutiny. A pat-down certainly lets the individual know he or she is being searched, positioning one to observe and challenge one’s treatment as a suspect. Terahertz imaging lacks this natural—if insufficient—check on abuse.

So terahertz imaging is not just a “hi-tech pat-down.” Its potential takes what would be a pat-down and makes it into a secret, but intimate, visual examination—a surreptitious strip-search. Pat-downs and secret strip-searches are very different things, and it is not necessarily reasonable, where a pat-down might be called for, to use terahertz imaging.

And that brings us to the fundamental problem with Commissioner Kelly’s proffer to use this technology at a “specific event” or at a “shooting-prone location.” These contexts do not create the individualized suspicion that Fourth Amendment law demands when government agents are going to examine intimate details of a person’s body and concealed possessions.

It is certainly possible to devise a terahertz imaging device and a set of use protocols that are constitutional and appropriate for routine, domestic law enforcement, but Commissioner Kelly hasn’t thought of one, and I can’t either.

Consider the dollar costs and potential health effects of terahertz imaging detection, it might just be that the pat-downs pass muster far better than the high-tech gadgetry.

I attended the Supreme Court’s oral argument in U.S. v. Jones today, the case dealing with the Fourth Amendment constitutionality of using GPS to track individuals’ movements without a warrant. Predicting outcomes is fraught, and you’re getting your money’s worth from the following free observations.

It seemed to me that most members of the Court want to rule that the government does not have free reign to attach GPS devices to cars. Justices Kennedy, Breyer, and Sotomayor, for example, noted the vast consequences if the government were to win the case. Law enforcement could attach tracking devices to people’s overcoats, for example, and monitor their movements throughout society without implicating the Fourth Amendment. Voluble as he often is, Justice Scalia did not say that the Fourth Amendment doesn’t reach GPS because GPS data wasn’t around for the Framers to insulate from government access.

Justice Alito’s thinking seemed to venture the furthest. He noted how insufficient it would be if the Court were to decide the case based on the narrow ground that attaching a GPS device to a car is an unreasonable seizure. Doing so would not account for the vast amount of personal data the government might access without attaching something to a car, clothing, or other property. If not in this case, the Court will soon have to face the (pernicious) third-party doctrine, which holds that a person has no Fourth Amendment interests in information shared with others.

If the Court desires to rule against the government, the one thing it lacks is a rationale for doing so. When it was time for Jones’s counsel to argue, the Justices seemed frustrated not to have a principle on which to base a decision.

Justice Scalia early-on declared his concern with GPS tracking and his dismay that the “reasonable expectation of privacy” test from Katz v. United States (1967) might shrink the zone of privacy the Framers sought to protect in the Fourth Amendment. But he later retreated into a sort of catch-all posture: the Congress can control GPS tracking if it wants. (Jones’s counsel cleverly suggested that there were 535 reasons not to do that.)

Other Justices’ questions danced awkwardly with the “reasonable expectation of privacy” test. Justice Kennedy was equivocal once about whether it would apply. Chief Justice Roberts seemed acutely aware of the Court’s incompetence to make judgments of such broad societal sweep. This is for good reason: there is no way to determine what society thinks, or what is “reasonable” in terms of privacy, when new technologies are applied new ways.

The solution to this conundrum can be found in the Cato Institute’s amicus brief in the Jones case. The Court should not use the “reasonable expectation of privacy” test from Justice Harlan’s Katz concurrence. Rather, it should follow the majority holding, which accorded Fourth Amendment protection to information that Katz had kept private using physical and legal arrangements. The government stands in the same shoes as the general public when it comes to private information—that is, information that can’t be accessed legally or with ordinary perception. When the government accesses information that was otherwise private, those searches and seizures must be reasonable and must almost always be based upon a warrant.

This way of administering the Fourth Amendment is not a snap of the fingers. There will be details to hash out when the Court eventually finds that having a Fourth Amendment interest in information turns on a factual question: whether someone has concealed information about him- or herself.

The biggest impediment to adoption of this rule may be getting lawyers to realize that “reasonable expectation of” is not a prefix required every time they use the word “privacy.”

If the government put a GPS monitor on your car and used it to track every vehicular movement of yours for four weeks, do you think that would violate your Fourth Amendment rights? The government would like to be able to do that kind of thing without getting a warrant, and the Supreme Court will soon decide whether it can.

On November 8th, the Court will hear oral argument in U.S. v. Jones. Yours truly was the lead author of Cato’s amicus brief in the case, which may have a significant effect on how Fourth Amendment law intersects with new information technologies for decades to come.

In 2004, suspecting that Antoine Jones was dealing drugs, the FBI secretly attached a GPS tracking device to his car without a valid warrant. The FBI used this device to monitor and record the car’s movements, noting its location every ten seconds when it was in motion, for nearly a month before finally arresting Jones. The U.S. Court of Appeals for the D.C. Circuit found that the FBI’s action was unconstitutional because it violated Jones’s “reasonable expectation of privacy”—the two-part Fourth Amendment standard developed in the landmark case of Katz v. United States. Though he traveled on public roads, the totality of his movements was available to nobody and thus was private.

Our brief argues that the government’s conversion of Jones’s vehicle into a surveillance device was an unreasonable seizure under the Fourth Amendment. Even though he didn’t lose a “possessory” interest in his car, the government invaded Jones’s various property rights, including the right to exclude, the right to manage, the right to use, and the right to the profits. Similarly, using his car to collect detailed data on his movements over this extended period without getting a warrant was an unreasonable search. The data reflecting his movements would never have come into existence without the government attaching its GPS device to his car. These are tough, interesting issues arising in the new circumstances created by information technology.

We spent as much time in the brief on the “reasonable expectations of privacy” test. The product of one Justice’s lone concurrence in the Katz case, it holds that if a person has an actual (subjective) expectation of privacy and that expectation is one society is prepared to accept, then the Fourth Amendment protects the object of that expectation.

Courts have never faithfully applied this test, and for good reason: it’s a doctrinal mess that reverses the Fourth Amendment’s focus. Courts have second-guessed what the citizenry thinks in terms of privacy rather than examining government action to see if it is reasonable. Under “reasonable expectations” doctrine, things that are left in plain view are always available to the government while things that are hidden—well, the Court will look to see whether keeping it private comports with “reasonable expectations.”

The majority ruling in Katz rested on physical and legal protection that Katz had given to the sound of his voice when he entered a telephone booth. Because Katz had secured the privacy of his conversation, the government wasn’t allowed to access it using a wiretap—not without a warrant. That’s the rule the Court should apply here. The government can’t use uncommon surveillance technology to access private information, including private information about things that happened “in public,” without a valid warrant.

With information technology still rapidly increasing in power, it is critically important that the Supreme Court update Fourth Amendment law while maintaining its consistency with ancient property principles. Doing so will ensure that technology doesn’t render the Fourth Amendment’s protections for our “persons, papers, houses, and effects” quaint.